The present invention relates to an apparatus and a method for an additional call setup for data transmission between a second data receiver and a data transmitter via at least one mobile telecommunications system, in which between the data transmitter and the second or a first data receiver, a first call setup has already taken place within a certain time period in the past.
Although applicable to arbitrary mobile types of data transmission over arbitrary data terminal devices, the present invention and the problems it seeks to solve will be explained here in terms of a telephone call made by a mobile telephone.
For a call setup for data transmission between two data terminal devices, the data transmitter and data receiver must be allocated certain physical resources, which in the mobile telecommunications system are available via an air interface connection. As a rule, this allocation takes place in a logical controller device, which in a mobile telecommunications system is usually called an RRC (Radio Resource Control) device. This device manages the physical resources of a transmission channel of the mobile telecommunications system.
In telecommunications systems that employ a CDMA (Code Division Multiple Access) method, which can be used for channel access, for instance in cellular systems for mobile radio, such as a UMTS (Universal Mobile Telecommunication System) system, a physical resource is defined either as a combination of a CDMA code and a carrier frequency of the applicable transmission channel, or else a third component—time—is added. In the first case, the term FDD mode (Frequency Division Duplex) is used, and in the latter, TDD mode (Time Division Duplex); that is, a radio resource of the transmission channel of the mobile telecommunications system is defined as a combination of a CDMA code, a carrier frequency, and a time slot.
Which ones of the still-available resources are allocated by the controller device to which data transmitter, in particular a mobile telephone, and how this allocation is carried out, are forwarded by the controller device by means of appropriate signaling to the data transmitter from which the applicable request had come. For UMTS systems, for instance, an applicable protocol for this signaling is defined with certain information elements.
Also in UMTS systems, a plurality of levels of protocols are defined, which are each addressed by the controller device.
In principle, for every mobile data transmitter and data receiver or mobile station, different logical channels (radio bearers), that is, channels inside the applicable mobile station, are processed with suitable data identification, advantageously in levels 2 and 3 of a UMTS protocol, and are sent on to the level 1 of the UMTS protocol in the form of various transport channels. This level 1 copies the transport channels onto various physical channels, that is, channels for instance of different frequency, with different code or time slots, or any combination of these three factors. These physical channels represent the radio resources. The execution of the copying in the various levels is defined unambiguously by the controller device in the mobile telecommunications system upon a call setup.
Thus each time a call is set up, the allocation of radio resources and the copying of logical channels onto transport channels onto physical channels must be forwarded completely and unambiguously from the mobile telecommunications system to the applicable mobile data transmitter. To that end, the signaling protocol is filled with a high number of signaling or information elements.
However, it often happens that a user of mobile telephone for instance completes a first telephone call, so that the first call setup is brought to a close, only to initiate a further telephone call shortly thereafter, for which he requires an additional call setup.
For such an additional call setup, in the prior art the fact that in the second, third and successive call setup for a second, third and successive telephone call, for instance, the resources that have just been released are needed again and must therefore be completely re-allocated, has proved to be disadvantageous.
The same is true for the internal configuration of the corresponding mobile data transmitter, since upon a new allocation of radio resources, a new internal setting of the applicable mobile data transmitter must also be performed.
Thus each time a call setup is newly made, a certain data traffic occurs over the air interface, which reduces the transmission capacity for the actual transmission data or user data.
Accordingly, the object of the present invention is generally to furnish a new call setup for data transmission and with a reduced data occurrence of signaling information.